Actual storage of electricity has long been limited to batteries and other systems with limited capacity such as flywheels, but virtual electricity storage is now possible by utilizing pumped water storage, ice storage and compressed air storage (CAES). Wind farms are faced with the problem of matching power availability with demand on a real time basis. Issues faced by wind farms include: o Wind availability may be low or absent during peak demand periods. o Wind energy may be abundant at night during periods of low electric power demand. There is no proven way to store electricity from wind farms. o Wind farms cannot offer significant energy quantities on a firm basis. Utility operated power plants sit idle for most of the nighttime resulting in underutilization of its equipment. Prior Art The most promising method for virtual electricity storage at combined cycle power plants involves the linking of a gas turbine combined cycle generation system (gas turbine+steam turbine) with compressed air stored at high pressure (CAES) in underground caverns or spent wells. Compressed air is produced and stored at night utilizing low cost nighttime power. During high demand periods (daytime) the stored compressed air is delivered to the gas turbine. These systems have been installed at several locations in the United States. Daytime power plant operation is based on withdrawal of stored compressed air for utilization as combustion air in the gas turbine. This enables the air compressor section of the gas turbine to “free wheel” while consuming little or no power. The full output of the gas turbine (more than twice the rated output) is then available as electricity during peak demand hours. Power plant revenues are increased significantly because more power is sold at higher prices while little or no power is wasted at night. A larger generator is required, but operating costs are nearly unaffected The problem facing CAES systems is that the power plant must be located adjacent to empty caverns such as salt domes or spent oil/gas wells. It is very uncommon to site power plants adjacent to empty caverns or spent oil/gas wells.
A planned and started transfer to the decarbonized power grids is based first of all on increased use of renewable (mainly wind and solar) energy sources. However with large shares of these technologies, it may be desirable to take steps to ensure the on-demand and reliable supply of electricity, taking into account a variable output of the renewable energy sources and a frequent both positive and negative unbalance between this output and a current demand for power. One of the possible ways for solving this problem is the use of large-scale energy storages in the decarbonized power grids.
Amongst the energy storage technologies able to accumulate a lot of energy and store it over a long time-period, a recently proposed Liquid Air Energy Storage (LAES) technology is distinguished by the freedom from any geographical, land, and/or environmental constraints inherent in other large-scale energy storage technologies such as Pumped Hydroelectrical Storage and Compressed Air Energy Storage. In addition, LAES technology is characterized by much simpler permitting process and a possibility for co-location with any available sources of natural or artificial, cold or/and hot thermal energy, which may be used for enhancement of its power output.
Known LAES systems have inefficiencies, and often do not use the cold fluids in the most efficient manners.
Thus there is a need for a process for compressed air energy storage that overcomes the above listed and other disadvantages.